Process and bath for copper coating ferrous metal



Patented June 7, 1949 PROCESS AND BATH FOR COPPER COATING FERROUS METAL Samuel C. Avallone, Cleveland Heights, and Arch W. Harris and Esther J. Whiting, Cleveland, Ohio, assignors to The American Steel and Wire Company of New Jersey, a corporation of New Jersey No Drawing. Application September 25, 1944, Serial No. 555,762

6 Claims. (Cl. 117-130) The present invention relates to a method of coating with a lubricating medium, ferrousmetals such as ordinary carbon steels and alloys thereof such as the stainless steels consisting of combinations of nickel and chromium or chromium alone, the purpose being to furnish a lubricating medium, in the form of a coating, on wire or strip, made from the aforementioned ferrous metals, which is to be subjected to cold forming operations such as wire drawing, stamping, cold heading, etc.

More specifically, for example, the invention pertains to a method of chemically coating stainless steel wires and rods with copper as a lubricating medium, whereby the rods and wire can be cold drawn without necessitating coating the same with lead, which is expensive and by no means entirely satisfactory when working with the finer gages of wire. It has been established in practice that rods or,wire coated with copper, when the coating has been-applied in the manner of this invention, can be given just as heavy reductions and drawn just as fast as is possible when lead coatings are employed and yet cost considerably less as compared with the use of lead coatings.

In accordance with the present invention, the copper coating is applied to the stainless steel or ordinary carbon steel wire being drawn by simply immersing the wire in a suitable aqueous bath containing, by weight, approximately 1.25% cuprous chloride, 1.25% ammonium chloride, 3.0% hydrochloric acid, 0.01% Carbowax #4000, the balance being water. In order to maintain the cuprous chloride in the reduced condition it is necessary to have scrap copper present in the bath. Metallic tin or stannous chloride can also be used to maintain the cuprous chloride in a reduced condition. The bath can be operated in the range between 70 F. and 195 F" t3; preferable range being between 180 F. and 1 F.

It is understood, of course, that the metal surfaces to be coated with copper by this invention must be chemically clean, that is, free of all extraneous matter, such as oxides, grease, etc., and at the same time not be passive so as to hinder the proper chemical reactions taking place between the coating bath and base metal to be coated.

The success of the above bath in plating copper onto ferrous metals and their alloys, such as 'the stainless steels, depends on getting the cuprous chloride in solution and thereafter keeping it in the reduced state. The cuprous chloride 2 is insoluble in water, but is soluble in an aqueous solution of ammonium chloride and hydrochloric acid. Any salt such as sodium chloride, calcium chloride, potassium chloride which will raise the solubility of the cuprous chloride in an aqueous solution can be substituted for the ammonium chloride. The scrap copper, metallic tin or stannous chloride are used to keep the cuprous chloride in the reduced or "ous condition. The Carbowax is an additive agent which serves to produce a fine grain copper deposit which makes it possible to deposit a greater amount of copper and at the same time obtain an adherent coating on ferrous metals and their alloys such as V the stainless steels.

The above bath can have its composition varied to a certain degree, that is, the ammonium chloride content can be varied from 0.4% to 20%, the cuprous chloride from 0.40% to 10%, and the hydrochloric acid from 2.0% to 12% with suflicient stannous chloride, metallic tin or scrap cop-' per added thereto to keep the cuprous chloride in a reduced state. Alsoaddition agents such as triethanolamine napthanate and commercial wheat flour can also be used instead of Carbowax, Carbowax being a registered trade mark of Carbide and Carbon Chemicals Company, New York, N. Y., for proprietary, synthetic, nonvolatile, water soluble waxes, Carbowax #4000 being composed of higher polyethylene glycols having an average molecular weight ranging from 3500# to 4500# determined by acetylation, "Carbowax #4000 thereby being a grade of the composition marketed under the trade mark "Carbowax. Any addition agent which would produce a fine grained copper deposit in conjunction with this bath could be used successfully. Approximately 1% of flour is used or between .01% and 0.2% Carbowax.

It has also been foundthat a bath from which the ammonium chloride has been omitted will function satisfactorily providing the hydrochloric acid content is sufficiently high to afiord the required solubility for the cuprous chloride.

The success of the coating baths described herein depends on keeping the cuprous chloride in the reduced state, and the use of an additive agent which will function in such a manner as to produce a fine grained deposit of copper.

Many efforts have been made heretofore to develop a method for chemically depositing copper on stainless steel, but without any degree of success. The present invention makes it possible to deposit a. relatively heavy coat of fine grained copper on stainless steels such as 18-8 (18% chromium-8% nickel) and the straight chromium types while even heavier fine grained adherent copper coatings can be applied to the ordinary straight carbon steels. It is found in practice that much heavier coatings of copper are capable of being applied to ordinary carbon steels than has been possible when using old prior art methods. The coatings though being many times heavier are fine grained and completely adherent to the ferrous base metal. The method described herein is very flexible in operation in that it lends itself to either continuous or batch type treatment and is more economical to use because it is not necessary to apply any electrolytic means thereto inasmuch as the method is one involving only straight chemical deposition.

We claim:

1. The method of chemically depositing fine grain copper coating on ferrous metal comprising immersing the metal in an aqueous bath consisting by weight of 0.40 to 20% cuprous chloride, 2 to 12% hydrochloric acid, 0.4 to 20% of an agent for enhancing solubility of cuprous chloride selected from the grou consisting of ammonium chloride, sodium chloride, calcium chloride and potassium chloride, and the remainder water, the bath being maintained at a temperature in the range 70 to 195 F. and in the presence of a reducing agent for preventing oxidation of cuprous chloride, the reducing agent being of the group consisting of metallic copper, metallic tin and stannous chloride.

2. The method of chemically depositing fine grain copper coating on ferrous metal as lubricant for cold working the metal comprising immersing the metal in an aqueous bath consisting by weight of 0.40 to 10% cuprous chloride, 2 to 12% hydrochloric acid, 0.4 to of an agent for enhancing solubility of cuprous chloride selected from the group consisting of ammonium chloride, sodium chloride, calcium chloride and potassium chloride, 0.01 to 0.20% polyethylene glycol of molecular weight 3500 to 4500, and the remainder water. the bath being maintained at a temperature in the range 70 to 195 F. and in the presence of a reducing agent for preventing oxidation of cuprous chloride, the reducing agent being of the group consisting of metallic copper,

metallic tin and stannous chloride.

3. The method of chemically depositing fine 4 bath being maintained at a temperature to F. and in the presence of a reducing agent for preventing oxidation of cuprous chloride, the reducing agent being of the group consisting of fietailic copper, metallic tin and stannous chlo- 4. As a bath for chemical deposition of copper on ferrous metals, an aqueous solution consisting by weight of 0.40 to 10% cuprous chloride, 2 to 12% hydrochloric acid, 0.4 to 20% of an agent for enhancing solubility of cuprous chloride selected from the group consisting of ammonium chloride, sodium chloride, calcium chloride and potassium chloride, and the remainder water, the solution being in the presence of a reducing agent for preventing oxidation of cuprous chloride, the reducing agent being of the group consisting of figtallic copper, metallic tin and stannous chlo- 5. As a bath for chemical deposition of copper on ferrous metals, an aqueous solution consisting by weight of 0.40 to 10% cuprous chloride, 2 to 12% hydrochloric acid, 0.4 to 20% of an agent for enhancing solubility of cuprous chloride selected from the group consisting of ammonium chloride, sodium chloride, calcium chloride, and potassium chloride, 0.01 to 0.20% polyethylene glycol of molecular weight 3500 to 4500, and the remainder water, the solution being in the presence of a reducing agent for preventing oxidation of cuprous chloride, the reducing agent being of the group consisting of metallic copper, metallic tin and stannous chloride.

6. As a bath for chemical deposition of copper on ferrous metals, an aqueous solution consisting by weight of approximately 1.25% cuprous chloride, 3.0% hydrochloric acid, 1.25% ammonium chloride, 0.01% polyethylene glycol of molecular weight 3500 to 4500, and the remainder water, the solution being in the presence of a reducing agent for preventing oxidation of cuprous chloride, the reducing agent. being of the group consisting of metallic copper, metallic tin and stannous chloride.

SAMUEL C. AVALLONE. ARCH W. HARRIS. ESTHER J. WHITING.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,969,553 Gernes Aug. 7, 1934 2,133,255 Rogers Oct. 11, 1938 2,217,921 Saukaites Oct. 15, 1940 

